Understanding Ankylosing Spondylitis


Ankylosing spondylitis is a complex, painful condition that can affect many parts of your body.

From the Greek words ankylos, meaning stiffening of a joint, and spondylo, meaning vertebra, ankylosing spondylitis (AS) is a complex, painful condition that can affect many parts of your body. However, AS most often causes pain and stiffness of the lower back because it attacks the sacroiliac joints between the spine and the pelvis. Over time, AS can damage the spine and lead to the growth of new bone. This causes the spine to stiffen and can result in a hunched-forward posture. Other parts of the body, such as the ankles, heels, ribs, hips, shoulders, and hands, can be affected. In rare instances, the eyes can be affected. Even the lungs and heart can become involved in AS.


Unlike other forms of arthritis, such as osteoarthritis, which is a wear-and-tear degenerative disease that is more common among women and older adults, AS generally develops earlier in life. AS usually develops in men younger than 40 years; however, but it can also affect women, children, and older adults.


The symptoms of AS can vary from person to person, but usually develop gradually over several months or years. At first, patients may not notice the signs of AS. In fact, AS often goes undiagnosed because symptoms can come and go. But over time, they can get worse. The earliest symptoms of the disease may include pain and stiffness in the lower back and hips, especially in the morning and after long periods of not moving. The Table lists the parts of the body most commonly affected by AS.

For most individuals, AS comes in painful episodes, or flares, followed by temporary periods in which symptoms subside. Over the course of the disease, symptoms can get better, get worse, or stop at irregular intervals. The pain often improves when patients are active and exercising.

In some cases, inflammation due to AS can make joints fuse together. This happens when ligaments turn into bone, causing the spinal bones to join. This fusing can affect the flexibility of the spine, giving some patients the hunched-forward posture previously mentioned.

AS can also lead to iritis or uveitis, conditions in which the eye becomes inflamed. About one-third of patients with AS experience iritis or uveitis at least once. Eye inflammation causes painful, red, watery eyes; blurred vision; and sensitivity to light. See your health care provider (HCP) right away if you develop these symptoms. In rare cases, patients with AS may experience bowel inflammation, which is related to Crohn’s disease and ulcerative colitis.


The cause of AS is unknown, but it is likely that genes and environmental factors play a role. AS tends to run in families, and the main gene associated with susceptibility to AS is HLA-B27. Individuals are at an increased risk of AS if they:

  • Test positive for the HLA-B27 genetic marker
  • Have a family history of AS
  • Have frequent gastrointestinal infections


Your HCP may suspect you have AS, but the diagnosis is often made by a rheumatologist, an expert in arthritis and rheumatic diseases. Diagnosis generally involves a thorough physical exam, which includes x-rays, a medical history, a look at family history of AS, and blood tests. In the physical exam, the rheumatologist looks for key signs of AS, which include the following:

  • Onset of disease usually before 35 years of age
  • Chronic pain, or pain that lasts for more than 3 months
  • Back pain and stiffness that worsens and leads to immobility, especially at night and in the early morning
  • Back pain and stiffness that improves with physical activity and exercise
  • Improved pain after taking nonsteroidal anti-inflammatory drugs (NSAIDs)

Your rheumatologist will be looking for pain and inflammation in areas of the body associated with AS, including the back, pelvic bones, sacroiliac joints, chest, and heels. Imaging tests may be used to look for changes in your joints and bones. These tests include x-rays, computed tomography (CT), and magnetic resonance imaging (MRI).

Blood tests may also be used in the diagnosis process. Although no blood test can spot AS, some blood tests can look for signs of inflammation. However, inflammation can be caused by a variety of health problems. Blood tests can also show if you have the HLA-B27 gene, indicating whether you have a higher risk of developing the disease.


Although there is no cure for AS, treatment can be effective in reducing pain and stiffness, and may stop or delay complications and spinal deformity. Treatment generally involves a combination of exercise, drug treatment, and physical therapy. If you have severe pain or joint damage, your HCP may recommend surgery.


NSAIDs reduce inflammation, relieve pain and stiffness, and are the most commonly prescribed drugs for treating AS. NSAIDs used in the treatment of AS include the following:

  • Naproxen
  • Ibuprofen
  • Indomethacin
  • Diclofenac

When NSAIDs do not work, corticosteroids, such as prednisone, methylprednisolone, and cortisone, may be used. These drugs are injected directly into the affected joints to bring quick but temporary relief. Disease-modifying antirheumatic drugs (DMARDs), such as sulfasalazine and methotrexate, also work to reduce inflammation due to AS.

If none of the above medications work, tumor necrosis factor (TNF) inhibitors are sometimes prescribed. These drugs block a cell protein called TNF, which promotes inflammation in rheumatic diseases such as AS. Blocking this protein can help relieve pain and stiffness while reducing tender or swollen joints. TNF inhibitors are injected into the skin.

TNF inhibitors used to treat AS include the following:

  • Humira (adalimumab)
  • Enbrel (etanercept)
  • Remicade (infliximab)
  • Simponi (golimumab)

As with most medications, the drugs come with some adverse effects. NSAIDs can cause gastrointestinal bleeding. TNF inhibitors can reactivate latent tuberculosis (a type of lung infection) and may lead to certain neurologic problems. Patients should be aware of these potential problems and notify their rheumatologist if they experience them.


Certain breathing exercises preserve and improve lung capacity. If AS has progressed and is causing the hunched-forward position, a physical therapist may recommend a variety of exercises to maintain good posture. Abdominal and back exercises, as well as sleeping and walking correctly, can help patients to remain stay upright.


Some patients require surgery to treat severe pain and joint damage. Knee surgery and hip replacement surgery are sometimes required when joints become severely damaged. Surgical correction may also be required for severe deformities of the spine.


AS is a chronic disease, meaning that it can last a lifetime. In the beginning, patients may have only mild symptoms they feel they can handle. This may be true, but it is still very important for them to see a rheumatologist at least once a year. An arthritis expert can help keep symptoms under control and spot underlying problems that may arise as a result of AS.

Beth is a clinical pharmacist and medical editor residing in Northern California.


  • Ankylosing spondylitis. National Institute of Arthritis and Musculoskeletal and Skin Diseases website. niams.nih.gov/health_info/ankylosing_spondylitis/ankylosing_ spondylitis_ff.asp. Published November 2014. Accessed June 13, 2016.
  • Reveille JD. Spondyloarthritis. American College of Rheumatology website. rheumatology. org/I-Am-A/Patient-Caregiver/Diseases-Conditions/Spondyloarthritis. Updated November 2013. Accessed June 13, 2016.
  • Mayo Clinic staff. Ankylosing spondylitis. Mayo Clinic website. mayoclinic.org/ diseases-conditions/ankylosing-spondylitis/basics/definition/con-20019766. Published February 11, 2014. Accessed June 13, 2016.

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